I have a 95' Dodge Dakota, is there anything I can do to it to upgrade it performance wise?

you can add a KN cold intake or equivalent, get headers, straight pipe the exhaust (or at least get a better flowing one than the stock), new spark plugs, use a lighter oil ( I like to use synthetics personally 5w-20 Mobil 1), use a performance oil filter. those are the basic things you can do to add just a little more pep without doing major work on it. If you want better performance in handling upgrade your brakes, grippe tires, change out the power steering fluid to a more responsive (I use lucas here), change the brake lines from rubber to braided. If you really want to get more performance you can add a turbo or start changing out the heads, rods, and cams. but if you get into that it is some major work and the engine may need to be re-tuned. Also you could change up the gear ratios or start lightening the truck up and change parts of the frame or accessories with carbon fiber or aluminum.

dump the 3.9 for a 5.2 or 5.9. you aren't going to squeeze much power from the 6.